Data archiving is a process of moving stored data that is not currently used to a separate data storage device for long-term retention. For example, data archives may include older data that is still important and necessary for future reference, as well as data that must be retained for regulatory compliance. Occasional access to this data may be necessary. As such, data archives are indexed so that the data (and parts thereof) can be readily located and retrieved. In contrast to data archives, data backups are copies of data used to recover data that is lost or corrupted. Backups are also used to recover data according to data retention policies.
Archive data and backup data (i.e., archive/backup data) in networked systems are often stored on devices that are not part of mainstream traffic. To conserve power, these storage devices may not always be powered-on except for occasions when data or read/write request is received.
Magnetic data storage devices are often used to store archive data and backup data (i.e., archive/backup data). A hard disk drive (i.e., “hard drive” or “hard disk”) is a non-volatile, random access digital magnetic data storage device. It includes rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the platters. Hard disk drives record data by magnetizing ferromagnetic material directionally. Sequential changes in the direction of magnetization represent patterns of binary data bits. The data is read from the disk by detecting transitions in magnetization and decoding the originally written data.
A failure of a hard disk drive can result in a loss or corruption of data. Such failures can be due to, for example: input/output stress to the hard drive, high-voltage fluctuations, physical shocks (drops, bangs, etc.), local magnetic fields (e.g., strong magnets, magnetic fields, and the like), age (most drives have a 3-5 year time-before-failure construction materials), and problem with associated devices (e.g., cooling systems, air filters).
Self-Monitoring Analysis and Reporting Technology (“SMART”) was developed to increase the reliability of hard disk drives. SMART predicts failures by incorporating diagnostics into hard disk drives that monitor the internal operations. When SMART detects a potential failure, the hard disk drive can be repaired or replaced before any data stored on the hard disk drive is lost or damaged.
While SMART may predict failures of hard disk drives, the data stored on the hard disk drives may not be actively monitored. For example, when a system stores data on a hard disk drive, it may verify that no errors occurred during transmission and/or storage. However, the data may be subsequently exposed to various sources of loss or corruption, including power fluctuations (e.g., during power-up and power-down), environmental changes (e.g., temperature changes, moisture, dusts, etc.), mechanical wear and tear (e.g., problem with air filters, exhaust fans, aging, etc.), and human activities (e.g., physical relocation, placement of nearby objects that affect magnetic fields, etc.). Any such loss or corruption may not be detected occur for a substantial period of time (e.g., when a request to read data occurs).